Alternating current vapor electrical device



Sept. 29, 1931. L, F; BIRD 1,824,760

ALTERNATING CURRENT VAPOR ELECTRICAL DEVIGB Filed Oct. 22. 1929 ATTORQIEY the tu Patented $ept. 29, 1931 UNTED STATES PATENT oF cE LESTER F. BIRD, NEWARK, NEW JERSEY, ASSIGNOR TO HANOVIA CHEMICAL AND MANUFACTURING COMPANY, OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY ALTERNA'IING CURRENT VAPOR ELECTRICAL DEVICE Application filed October 22, 1929. Serial No. 401,600.

mercury arc lamp or a hot cathode neon arc lamp, it is carried by an are through the mercury vapor or the neon gas. The arc is a 19 source of li ht, and may be seen through the quartz or g ass envelope in which the vapor or gas is contained. A small arc of high intrinsic brilliancy will produce as much light as a large lamp of relatively lower intensity. 15 Ina mercury arc lamp a quartz envelope is sometimes used, and the cost of an arc tube is roughly proportional to the weight of the quartz used in its manufacture. Consequently it is desirable from an economic standpoint that the size of the uartz envelope be kept as small as possible. here are limiting conditions of operation for all types of enclosed arc lamps, this being especiall true of gas 01 vapor filled arc lamps. he mercury arc M stream in a quartz tube, for instance, is ordinarily an extremely hot path of incandescent particles. 7

If this are stream touches the enclosing quartz envelope, it causes degeneration of the quartz. If, therefore, is desirable that the arc stream be constricted as much as possible to prevent it from coming in contact with the walls of the containing vessel. This may be accomplished to a certain extent by design of e and by operation at the proper voltage and current. As the voltage across a given tube is increased, the current is raised somewhat and the vapor pressure within the tube is increased. The increase in vapor pressure causes constriction of the arc stream. There is a limit to the increase in input to the burner, however, since a condition is soon reached when the burner current falls off with a continued increase in voltage and the arc becomes very unstable. Near this point the light output of the burner is a maximum and a farther increase in voltage does not produce any increase in light output. This limitation in input and instabilit of the are very dehnitely limit the possib e output from a mercury arc burner in the form of light ener It is an object of this invention to provi e a circuit arrangement such that the input to a vapor or gas lamp is not limited by the usual conditions of voltage and are instability, and with a given voltage to increase the intensity of the output.

A furher object is the provision of means for increasing the output of a'vapor or gas lamp without deteriorating effect upon the quartdz envelope in which the vapor is contalne i These and other objects are attained by the novel construction, combination and arrangement of parts hereinafter described and shown in the accompanying drawings, constituting a material part of this disclosure, and in which:

Fig. 1 is' a diagram of a 'common circuit employed for the operation of a vapor or gas filled lamp, and

Fig. 2 is a diagram showing the manner in which my invention is applied to the circuit shown in Fig. 1. 1

Referring to Fig. 1, the usual circuit is shown to include a source of alternating current having terminals 4,5 and a resistance 6' in the primary of a transformer 7. The secondary of the transformer has terminals 8 and 9, and a mid-tap 10, to which is connected a reactor 14, the latter being in turn connected to the cathode 13 of a mercury vapor arc lamp 15. The transformer terminals 8 and 9, are

respectively connected to the anodes 11 and 12 of the lamp 15. Current flows alternately in one of the anodes through the mercury vapor in the lamp and out the cathode. Arcs of this character are essentially rectifiers and are ordinarily constructedand connected so that ferently, the difference depending upon the relative amounts of unidirectional and alternating currents present.

Since the current from the burner flows through the burner circuit, any resistance in the circuit causes an apparent direct current potential difference to appear across the burner terminals. If the resistance of the circuit were zero, this direct current potential across the burner terminals would be zero, but, since there is always resistance in the burner circuit, there is always an apparent direct current potential across the burner.

I have found that the presence of this direct current potential across the burner indicates an inequality between the two halves of the alternating current cycles existing between an anode and the cathode. Because of this inequality an alternating current voltmeter across a burner may indicate a hundred volts of alternating current potential while a direct current voltmeter across the same terminals may indicate only fifteen volts. This value of fifteen volts is a measure of the unbalance or inequality in the halves of the alternatin current cycles.

I have ound further that this direct current potential across a burner reduces the effective potential drop between a working anode and the cathode at any instant. The alternating current potential across the burner is fixed by the transformer, and the anode having the greatest positive potential with respect to the cathode at any given instant is the one that is working.

The alternating current makes the working anode positive with respect to the cathode while the indicated direct current potential makes the cathode appear positive with respect to the anode. The result of the existence of an apparent direct current potential is to reduce the effective alternating current potentials at all times.

For this reason I have found that as the indicated direct current voltage is increased, the input power to the burner is reduced. Conversely, a reduction in the direct current potential increases the input power to the burner. Because of the fact that the light output of the burner follows closely its power input, I have determined that any means that will reduce the indicated direct current potential across the burner will increase the input to the burner and also will increase its light output.

I have found that, if this apparent direct current potential is actually reversed in direction by the application of sufficient external voltage, the input to a burner can be increased considerably beyond the point of normal equilibrium and that the output can be correspondingly increased. This reversal is accomplished by the addition of actual direct current potential in series with the cathode lead of the burner in such a direction as to apply the negative pole of the external supply to the cathode. The positive end of the external supply is connected thru the circuit to both anodes. The external source of direct current may be any kind of direct current supply since I have successfully used storage batteries, direct current generators, rectifiers and even rectified current of other frequencies than that for the burner.

In Figure 2 is shown a circuit in whic a storage battery 16 has been introduced, the

negative terminal of the battery being con-.

nected to the cathode 13. This arrangement provides a direct current potential in opposition to the apparent direct current potential between the anode and cathode, which results in decreasing the apparent direct current potential and increasing the power input to the burner.

By regulating the potential of the opposing direct current supplied by the battery 16, the intensity ,of the light output of the burner may be increased greatly, the alternating current potential remaining constant.

In the vapor filled type, the current flow is limited by the vapor pressure which in turn depends on the temperature of. the arc tube. Since-there is unvaporized liquid present at all times in the mercury arc lamp,-

a rise in temperature causes an increase in the vapor pressure. These conditions are different in the gas filled arc, there beingnoliquid in this type of arc tube. The amount of gas enclosed in the tube is fixed at the time when the tube is constructed. For these reasons there is no limitation of input due to increasing vapor pressure in the gas filled type. As a consequence an increase in voltage is followed by an increase in current unless the current is limited by other causes.

Since the light output of the gas filled lamp follows the input power quite closely, the output of this type of arc can usually be increased by applying higher voltages. The increases in output that can be secured from the application of my invention to the gas filled type of arc are not so striking as those from the vapor filled type, nevertheless there are certain advantages that can be secured by such an application.

The gas filled arcs are limited as to the maximum voltage that can be applied because of undesirable arcing between the anodes of such n arc. In some cases this becomes the limiting condition for increased output from a given burner. My invention permits a desirable increase in the input to such an arc and so a corresponding increase in light output without having to increase the applied volt ge across the burner termianls. In fact it is possible to secure a very great increase in'the light output with the applied voltage actually materially reduced.

Sources of direct current, other than a battery, have been tried and proved equally to the cathode of the lamp to impress on the efiicacious. The location of the direct curlamp 2. direct current potential in opposition rentsource in the circuit is of no consequence to the indicated direct current potential of the since the success of the invention does not 1am depend upon the location of the voltage in T is specification signed this 19th day of the circuit. Any arrangement of direct cur- October, 1929. 1

rent voltage sources that produces a reduc-' tion or reversal of the indicated direct current voltages normally existing across an operating alternating current gas or vapor arc lamp are applications of the invention.

While my invention has been described in use specifically with a mercury vapor arc lamp or a hot cathode neon arc in a glass envelope, it is in no sense limited in its application to such arcs, as it will operate equally well when used in connection with other arcs of a similar type or with other vapo or gas filled electric devices.

Having thus described my invention what I claim as new, and desire to secure by Letters Patent is:

1. In combination with a vapor or a 'gas filled electric lamp 'for operating on alternating current, a source of alternating current connected with the lamp, means for impressing upon the lamp a direct current potential in opposition to the indicated direct current otential normally existing between the ano es and cathode of the lamp while operating.

2. In combination with a vapor or a gas filled electric lamp for operating on alternating current, a source of alternating current connected with the lamp, a source of direct current in series with the cathode of said lamp, the negative terminal of said direct current source being connected to the cathode to impress upon the lamp 2. direct current potential in opposition to the indicated direct current potential of the lamp.

3. In combination with a vapor or gas filled electric lamp for operating on alternating current, a source of alternating current connected with the lamp, a source of direct current having its negative terminal connected to the cathode of said lamp to maintain the cathode at a negative indicated direct current potential with respect to the anodes while the lam is operating.

4. In combination with a vapor or gas filled electric lamp for operating on alternating current, a source of alternating. current connected with the lamp, and a storage battery in series with the lamp and having its negative terminal connected to the cathode of the lamp to impress on the lamp a direct current potential in opposition to the indicated direct current potential of the lamp.

5. In combination with a vapor or gas filled electric lamp for operating on alternating current, a source of alternating current connected with the lamp, and a source of unidirectional current in series with the lamp and having its negative terminal connected LESTER F. BIRD. 

